This invention relates to seat belt retractors. Due to safety regulations, substantial improvements have been made in the structural design of such devices. Normally, they include spools or spring biased reels which payout a safety webbing about a passenger and simultaneously facilitate his comfortable movement in the buckled position. Further, these safety webbing devices have the capability to sense and lock against webbing payout in the event of a collision or overturning of the vehicle, and this capability is usually accomplished through the use of webbing sensitive lock or a vehicle sensitive lock.
The webbing sensitive locks are illustrated by U.S. Pat. No. 3,450,368, and may employ a rotational spring biased centrifugal counterweight to measure the rate of webbing payout and lock the unit when the rotational force on the counterweight exceeds the associated spring bias. The vehicle deceleration locks may be illustrated by U.S. Pat. No. 3,578,260, in which a pendulum, pivoted by a rapid deceleration, locks the webbing against further payout. Moreover, as in U.S. Pat. No. 3,819,126 both systems have been incorporated into a single retraction device. The device of that patent includes only one locking pawl operable by either a vehicle sensitive or a webbing sensitive actuator. Movement of the pawl toward a locking position may be initiated by whichever sensor first reacts to a change in vehicle condition. Should that movement fail to lock up the reel, there is no reserve function available to accomplish locking of the reel. These prior devices do not, however, provide the safest assurance and simple design of the instant invention.